Cylindrical strainer or filter units



May 22, 1956 Filed April 2 1951 P. J. GROSPAS CYLINDRICAL STRAINER OR FILTER UNITS 3 Sheets-Sheet 1 :2 vllzA/fmt JOSEPH GROSPA 5 y 2. 1956 P. .1. GROSPAS 2,746,552

CYLINDRICAL STRAINER OR FILTER UNITS Filed April 2, 1951 3 Sheets-Sheet 2 N V {N 7 D It P/EAAE JOSEPH (1% mm 3 Sheets-Sheet 5 Filed Ap gil 2, 1951 I n 51v fa/E P/ERRE J05PH GROSPAS new I the successive turns of the helix.

United States Patent CYLINDRICAL STRAINER 0R FILTER UNITS Pierre Joseph Grospas, Casablanca, Morocco, assignor to Societe anonymegdite: Etablissements Grospas, Casablanca, French Morocco This invention relates to cylindrical strainer or filter unit or well liners, of the type providingan entirely free and unobstructed cylindrical inner space and having a comparatively thin outer wall in which calibrated apertures or gaps are provided. This type of liner is extensively used in oil Wells drilled through unconsolidated sandy formations and for similar purposes.

In known liners of this kind, the apertured outer wall generally consists of a heIically-wound strip of sheet material and the calibrated gaps therein are defined between It is obviously difiicult to wind sucha strip in such a way that the prede termined calibrated dimension is uniformly obtained between the successive turns of the helix, and the winding operation requires the use of specially constructed and expensive apparatus. Moreover, liners of predetermined length can only be produced in this way.

It is an object of this invention to provide an improved liner construction for the purpose described which is very.

simple to construct, assemble and disassemble while ensuring greater accuracy in the provision of the calibrated gaps. A further object is to provide such a linerwhich is built up from identical, standard, similar elements to any required length. Another object is to provide such a liner in which a damaged or worn part may easily be replaced by removing the corresponding standard element and replacing it with another. And yet another object is to provide such a liner in which the calibration of the gaps may be varied according to requirements by substituting one size of spacer element by another.

The above and further objects of the invention will appear as the description proceeds. I

With the said objects in view, my invention essentially provides a well liner structure which comprises a plurality of similar stacked rings retained in stacked coaxial assembly, with arcuate gaps defined between the adjacent sides of adjacent rings by means of spacer parts or" calibrated dimension interposed between the rings.

The said spacer parts may be formed integrally with the rings, being provided by the ends of blocks integral with each ring and projecting by a desired calibrated mounted inwardly or outwardly thereof. Means are then provided in the form of a radial flange extending from the base of the ring inwardly or outwardly as the case may be into engagement with the outer or inner wall of the apertured guide tube to define an annular chamber through which the fluid may freely flow from the gaps between the rings into the unobstructed cylindrical inner space of the liner assembly. Alternatively, the strainer rings of theinvention may be used by themselves with- 2,746,552 Patented May 22, 1956 2 out any associated guide tube, and tie-rods are then provided for interassembling the rings.

A few exemplaryembodiments of the invention will now be described in detail with reference to the accompanying drawings wherein:

Fig. 1 is a view in elevation of a filter unit with rings provided with projections, assembled around an inner guide tube;

Fig. 2 is a corresponding transverse section between two adjacent rings, on an enlarged scale;

Figs. 3 and 4 are partialradial sections respectively on lines III-III and IV-IV (Fig. 2);

Fig. 5 is a section similar to Fig. 2 in the case of ring sections assembled on an outer guide tube;

Figs. 6 and 7 are sections on lines VI-VI and VII-VII of Fig. 5;

Fig. 8 is a section similar to Figs. 2 and 5 relating to a construction wherein assembly is effected by tie-rods and wherein the spacer shims are in the form of separate inserts;

Figs. 9 and lOare' cross sections on lines IX-IX and XX respectively of Fig. 8.

The liner shown'in Fig. 1 consists of a tube section 1 providedat both ends with means of assembly such as an internally threaded bushing 2 and an external screw threaded portion 3, formed along its surface with perforations 4 distributed in any desired pattern along its length and periphery. Surrounding-this tube section in stacked relationship are rings 5 according'to theinvention, between which integralorseparate spacer'elements or shims or inserts 6 are interposed which retain the rings at their relative spacings and which are to be more fully described later.

This stack may be very simply made by providing a flange or a separately adapted ring 7 (e. g. welded), on the tube and then retaining the stack in a suitably compressed condition by a further ring 7 which may be secured to the tube by any appropriate means.

The rings 5, consisting of any appropriate rigid material (such as metal, plastic materials, concrete, etc.), externally possess a'cylindrical surface and are bevel cut on one end surface as shown at 8 over the greater part of their radial width dimension. Formed over the remaining part of the end surface of the ring are a plurality of bosses 9 (four as shown) the upper ends of which may project by a calibrated amount e beyond the upper plane of the ring to define the integral spacers 6. The width L of the spacers is smaller than the width of the ring so as to provide an annular bearing surface 10 having the width 1, extending the bevel portion 8 and defining between the tube 1 and the spacers an annular space for the flow of the liquid. As a result of this arrangement, the successive rings 5, 5', etc. may be stacked in any de sired relative angular position without having to pay attention to the relative positions of their bosses 9 and 9 with respect to the apertures 4 in the tube, the path of the liquid flow between the rings and through the tube 1 being indicated by the arrows. The larger sand particles or other impurities are arrested by the slots having the height e formed in the stack of rings, and it will be noted that owing to the provision of the bevel 8, said slots do not present any transverse surface in which the sand or other impurities might tend to collect.

The rings shown in Figs. 5 to 7 are designed for being mounted within an outer tube 1. They difier from the type of rings previously described in that the annular part 10 allowing the liquid to flow freely about the stack is provided outwardly rather than inwardly.

The rings shown in Figs. 8 to 10 are designed to make it possible to assemble the stack wtihout the use of a centering tube, by means of tie-rods 11 extending through holes 12 provided in the solid portion of the ring; that is through the bosses or blocks 9. The spacer shims 6 in this case are preferably provided as separate removable inserts, that is, independent from the part 9 on which they bear and are positioned by simply threading them over the tie-rods 11. It is also possible to alter the calibration of the filter without having to replace the rings merely by changing the size of the inserts 6. The same separate removable spacer shims may be provided in the embodiments of Figs. 1 to 7 It will be observed that owing to the fact that the liner has no centering tube and that the spacer shims all lie in the same radial position, it is not required herein to provide annular portions.

The invention is not limited to the arrangements and particular shapes of ring members and types of assembly described and illustrated in the exemplary embodiments shown herein.

What I claim is:

1. In a well screen comprising an apertured guide tube having apertures spaced throughout the length thereof, a stack of separate rings mounted co-axially with said tube to define an annular space therebetween and calibrated longitudinal spacer elements between adjacent rings defining a predetermined axial space therebetween, the provision of radial spacer elements between said rings and said tube comprising a thin circular flange extending from each ring into continuous contact with said tube and partitioning the space between said rings and tube into a series of separate, circular, horizontal chambers.

2. A well screen as inclaim 1, wherein said flange ex-- tends inwardly of said rings, said guide tube being positioned inside said rings.

3. A well screen as in claim 1, wherein said flange ex- 4 tends outwardly of said rings, said guide tube being positioned outside said rings.

4. A well screen as in claim 1, wherein the longitudinal spacer elements are separate and removable, thereby to enable variations in the screen calibration by exchanging the spacer elements.

5. A well screen as in claim 1, wherein the spacer elements are integral with the rings.

References Cited in the file of this patent UNITED STATES PATENTS 893,070 Gobbi July 14, 1908 1,570,725 Benckenstein Jan. 26, 1926 1,591,852 MacArthur July 6, 1926 1,688,326 Boulade Oct. 23, 1928 1,705,848 Austin Mar. 19, 1929 1.787,634 Laubner Jan. 6, 1931 1,849,042 Pickard et a1. Mar. 8, 1932 1,962,048 Altpeter June 5, 1934 1,976,217 Diepenbrock Oct. 9, 1934 1,991,286 Mandahl Feb. 12, 1935 1,995,850 Harter Mar. 26, 1935 2,000,490 Mandahl May 7, 1935 2,031,165 Johnson Feb. 18, 1936 2,063,367 De La Roza Dec. 8, 1936 2,284,787 Winkler June 2, 1942 2,359,475 Gauthier Oct. 3, 1944 FOREIGN PATENTS 30,652 Netherlands Sept. 15, 1933 107,090 Great Britain June 21, 1917 327,663 Italy July 17, 1935 

